The instant invention pertains to a motorized lever-action vertical axis coil grab adapted to be employed in suspension from an overhead crane or other such materials handling equipment for manipulative operation by one individual from a remote control location, wherein said grab provides a combined electromechanical and pivotally linked self-gripping means for clampably engaging an upright standing coil of wrapped metal material, and thereafter securely retaining the same throughout crane elevation and movement from one location to another, further wherein the grab means structure hereof additionally embodies for operational enhancement purposes a tong latch sensing switch assembly automatically operable to de-energize the crane hoist motor and prevent elevation or movement of an improperly grab-engaged coil so as to thereby avoid encountering both the hazard and problem of a coil slipping apart and out of the gripping device clamps as is otherwise frequently resultant when a coil is engaged thereby but not held therein with sufficient compressive force.
In a general mechanical sense, the instant invention structurally relates to that type of coil lifting grab as taught in U.S. Pat. No. 3,153,555 to Kaplan et al dated Oct. 20, 1964, and variations thereon as further taught respectively in U.S. Pat. No. 2,536,932 to Heppenstall dated Jan. 2, 1951, U.S. Pat. No. 2,803,489 to Zito et al dated Aug. 20, 1957, U.S. Pat. No. 2,830,842 also to Heppenstall dated Apr. 15, 1958, and U.S. Pat. No. 3,037,806 dated June 5, 1962, and U.S. Pat. No. 3,076,674 dated Feb. 5, 1963, both of the latter to Anderson.
Alternative to the foregoing teachings, and that of the instant invention is the heavy duty coil grab device as taught in U.S. Pat. No. 2,906,555 to Heppenstall dated Sept. 29, 1959, or U.S. Pat. No. 2,945,609 to Benes et al dated July 19, 1960, which service capability the instant invention is able to provide without, however, the structural mass requirements otherwise necessary in a heavy duty grab.
Maintenance of grab balance in various configurations of use employment in accomplishing coil movement operations is another advantageous grab capability, and the teaching set forth in U.S. Pat. No. 2,370,528 to Fontaine dated Feb. 27, 1945, shows a coil grab device provided with an adjustable center of gravity means for maintenance of operational use employment balance.
The instant invention incorporates use of a lost motion slot structure for accommodating both re-cycle set of the grab prepatory to coil engagement re-use employment and to accommodate engagement of tightly wrapped coils, as contrasted to the so-called lost motion slots shown respectively in U.S. Pat. No. 2,535,911 to Frame dated Dec. 26, 1950, and U.S. Pat. No. 3,680,907 to Siegwart dated Aug. 1, 1972, the latter slot applications of which are necessary to accommodate structural relief of frictional binding build-up forces encountered in link member translational movement during routine coil engagement use employment of said latter mentioned grabs in operation and do not per se provide true "lost motion" functions.
The tong latch mechanism employed in the instant invention is structurally and functionally similar to those as respectively taught in U.S. Pat. No. 1,506,827 to Gellert dated Sept. 2, 1924, and U.S. Pat. No. 1,839,389 to Heppenstall dated Jan. 5, 1932, however, the additional embodiment in the instant invention of a spring operable load sensing switch with the tong latch is distinguished over those of such similar embodiments as respectively taught in U.S. Pat. No. 2,060,722 to Breslav dated Nov. 10, 1936, and U.S. Pat. No. 2,718,321 to Westermeyer dated Sept. 20, 1955.
Certain other similar structural and functional features of the instant invention, such as clamp shoes having pivotally compensating retaining capability being respectively taught in U.S. Pat. No. 2,374,120 to Mueller et al dated Apr. 17, 1945, and U.S. Pat. No. 2,974,995 to Calhoun dated Mar. 14, 1961, or means for locking the grab clamping jaws in compressed engagement with the engaged coil thickness section as respectively taught in U.S. Pat. No. 2,718,321 to Westermeyer dated Sept. 20, 1955, and U.S. Pat. No. 2,803,489 to Zito et al supra, are set forth in the above-cited prior art disclosures.
It should be understood that some of the features of the instant invention have, in some cases, structural and functional similarities to certain of those teachings separately set forth in the prior art disclosures heretofore cited and briefly discussed. However, as will hereinafter be pointed out, the instant invention is distinguishable from said earlier inventions in one or more ways in that the present invention has utility features and new and useful advantages, applications, and improvements in the art of motorized lever-action vertical axis coil grabs not heretofore known.